This invention generally relates to a vascular catheter assembly having a movable guidewire therein and particularly to such a catheter assembly which is suitable for percutaneous transluminal angioplasty procedures (PTCA).
In typical PTCA procedures, a guiding catheter is percutaneously introduced into the cardiovascular system of a patient through the brachial or femoral arteries and advanced therein until the preshaped distal tip of the guiding catheter is in the ostium of the desired coronary artery. A dilatation catheter having a balloon on the distal end thereof and a guidewire slidably disposed within an inner lumen thereof are introduced through the guiding catheter. The guidewire is first advanced through the distal tip of the guiding catheter into the patient's coronary vasculature until the distal end of the guidewire crosses the lesion to be dilated. Then the dilatation catheter is advanced over the previously introduced guidewire until the dilatation balloon on the distal extremity of the catheter is properly positioned across the lesion. Once in proper position across the lesion, the flexible, relatively inelastic balloon is inflated to a predetermined sized with radiopaque liquid at relatively high pressures (e.g , greater than 8 atmospheres) to radially compress the atherosclerotic plaque of the lesion against the inside of the artery wall to thereby dilate the lumen of the artery. After a short period (e.g. less than 30 seconds) the balloon is deflated so blood flow is resumed through the dilated artery and the dilatation catheter can be removed.
Further details of angioplasty procedures and the devices used in such procedures can be found in U.S. Pat. No. 4,332,254 (Lundquist); U.S. Pat. No. 4,323,071 (Simpson-Robert); U.S. Pat. No. 4,439,185 (Lundquist); U.S. Pat. No. 4,468,224 (Enzmann et al.) U.S. Pat. No. 4,516,972 (Samson); U.S. Pat. No. 4,538,622 (Samson et al.); U.S. Pat. No. 4,554,929 (Samson et al.); and U.S. Pat. No. 4,616,652 (Simpson) which are hereby incorporated herein in their entirety.
Steerable dilatation catheters with built-in or fixed guidewires or guiding elements are used with greater frequency because their deflated profiles are generally smaller than conventional dilatation catheters with movable guidewires having the same inflated balloon size. Moreover, the fixed guiding elements in the steerable dilatation catheters provide considerably greater pushability which allows them to cross much tighter lesions than dilatation catheters with movable guidewires. Further details of steerable dilatation catheters may be found in U.S. Pat. No. 4,582,181 (Samson), U.S. Pat. No. 4,619,263 (Frisbie et al.), U.S. Pat. No. 4,641,654 (Samson et al.), and U.S. Pat. No. 4,664,113 (Frisbie et al.) which are hereby incorporated in their entirety by reference thereto.
While the tubular members forming the catheter body utilizing a movable guidewire could be made from stiffer material or thicker walled tubing to increase the pushability of the catheter, such added stiffness would reduce the flexibility of the distal end of the catheter which allows the catheter to pass through the tortuous passageways of a patient's vascular system.
What has been needed and heretofore unavailable is a movable guidewire dilatation catheter system having increased stiffness to improve pushability without the loss of the distal flexibility necessary for the advancement thereof through a patient's vascular system. The present invention satisfies that need.